Drawn by the promise of dazzling subterranean scenery, Nate Smith, Simon Jones, and Jarin Troxel set out to explore Wyoming’s Darby Canyon Wind and Ice Caves from nearby Rexburg, Idaho, one Saturday in May 2013.

Smith and Jones were friends at Brigham Young University’s Rexburg campus; their buddy Troxel was on leave from the college. Smith and Troxel had navigated the cave system the previous autumn, but neither had done any other technically demanding routes like this one that would require climbing and rappelling, and Jones was a complete novice. But the young men were fit and equipped with climbing ropes, headlamps, and snacks.

The trio left their car at the Darby Canyon trailhead at about noon, hiked up the snowy mountainside, and reached the mouth of the ice cave at 3 p.m. Judging by Smith and Troxel’s earlier expedition, they expected to reach the end of the Wind Cave to exit about ten hours later. The descent began with an exhilarating slide down an icy slope, then a 75-foot rappel down a frozen waterfall. They moved through a chamber of stalactites and another carpeted with transparent globes the size of dinosaur eggs.

Soon afterward, the men came to passages so low that they were forced to belly-crawl. Troxel had brought directions he’d found online, but they were hazy; several times, the group hit what seemed like dead ends and were forced to reverse course. At 3 a.m., they came to a rushing river where there should have been a narrow creek. Smith and Jones went off to investigate, while an exhausted Troxel lay down on the rocks and took a nap.

When the scouts returned, they reported that the river would indeed lead them out of the cave system. Afraid that the fast-moving water might sweep him downriver, Troxel fastened a rope to a small stone arch to stabilize himself. But as he set foot into the water, the arch gave way, and he tumbled into the frigid river. “I’m OK, guys,” Troxel said, getting to his feet. But his clothes were soaked, and as he refastened the rope to a more secure pillar, he was shaking with cold. After fording the river and a hip-deep pool, Smith and Jones were shivering too. The trio managed to rappel down a 20-foot-deep pit without incident, but as Troxel clambered down the other side, he fell again. Once more he insisted he was fine.

A while later, the men reached a cave about ten feet in diameter; the floor was covered with ice that rose into a small mound at the far edge of the chamber. This mound, Troxel said, was the ice plug that blocked the exit throughout winter and into spring. There had been no plug during his earlier visit to the cave with Smith. Still, he thought it could be cut through easily with his ice ax.

Troxel took turns with the others whacking at the mound. But the slope of the roof made it impossible to get a good swing. For hours, the men rotated between chopping, resting under a space blanket, and pacing to keep off the chill. Sleep was out of the question—after dozing for a few minutes, they would jolt awake with chattering teeth. To keep up their spirits, the men prayed and told jokes. By mid-morning, however, they had a new reason for worry: As the hole in the ice plug slowly deepened, it filled with slushy meltwater, which splashed them with each ax blow and further reduced the blade’s impact. None of them said what they were all thinking: At this rate, we’ll never break through.

Around 4:30 p.m., Smith saw light penetrating the ice from the other side of the plug. Hearing faint voices, the men began shouting for help. Someone yelled back, “We’re coming!”

It took another 45 minutes for members of the Teton County Search and Rescue team to clear away the four-foot-thick plug. Finally, a man in a hard hat climbed through the narrow opening. The search had begun that morning, the rescuers explained, when Smith and Jones’s roommate, Denis Tang, called to report them missing. Two dozen volunteers had combed Darby Canyon on snowshoes and in snowmobiles and ATVs.

Team members guided Troxel, Smith, and Jones through the last stretch of the Wind Cave, and the trio stepped into daylight for the first time in 27 hours. When the young men reached the trailhead, at 7:30, friends and family members rushed to embrace them. “Seeing how many people loved and supported us was overwhelming,” Jones said. “We’ve come to recognize the value of preparedness.”

All told, the guys weren’t seriously injured, and the incident hasn’t diminished their love of spelunking. They even plan to return to the caves this summer.